Tech Tips!

by Jonathan Teraji

YSR Stock Carb
1. Spring (Throttle Valve)
2. Jet Needle Assembly
3. Throttle Valve (Slide)
4. Throttle Stop Screw (Idle Adjustment)
5. Air Screw
6. Choke
7. Pilot Jet
8. Main Nozzle (Needle Jet)
9. Main Jet
10. Valve Seat Assembly
11. Float
12. Float Pin
13. Float Bowl
14. Drain Screw

 

Stock

YSR Carb

 
Float Bowl removed


 

Cap

Spring

Keeper

Needle

Slide


 
Three Pin holes, and two on the other side must be clean


 
Your carb could have either of these types of main jets


 

 
Your Carb could have either of these types of needles

Specifications for Stock YSR Carb
Main Jet 120
Pilot Jet 17.5
Jet Needle 3G21-4
Needle Jet E-0
Slide Cut Away 2.0
Air Screw 1 1/8
Valve Seat 1.5
Float Height 21~23mm

When cleaning the carb, pay particular attention to # 7 pilot jet, and #8 Needle jet. Along the shaft of the needle jet are 5 very small pin holes. Carb Cleaner won't even touch these! Take one strand of elecrical wire and "ream" out the 5 holes. Then cover one end of needle jet with your finger and shoot contact cleaner in the other end. You should see 5 streams of contact cleaner come out of the 5 pin holes. Do the same to the pilot jet.
Graph showing interaction of Carb Components
Interaction of Components

That's it for this month, shoot me some E-mail if you have specific YSR questions and I'll do my best to answer them as time allows, and/or suggestions for topics in "Tech Tips!" Remember this page is for you!

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